Trimming mechanism for sewing machines



Jun@ 24, 1ML M KNAUS 224mm TRIMMING MEGHANISM FOR SEWING MACHINES Filed Sept. 8, 1939 2 Sheets-Sheet l June 4, WML.

N. KNAUS TRIMMING `MECHANISM FOR SEWING MACHINES Filed Sept. 8, 1959 2 Sheets-Sheet 2 narran Patented June 24;, i941 'stares ear anar/57 anni? est 2 *lorries 6 claims. rc1. i12-122) This invention relates to trimmer-mechanisms forisewing machinea more particularly ofthe overedge type disclosed in my copending application, Serial No. 278,393, iiled June 19,1939.

Thepresent invention has for an object to improve sewing machine trimming mechanism, such as that disclosed in my said copending application, so that grinding of thetrimmer-knives will be required `only at infrequent intervals. p

Another objectof the invention is to provide the trimming mechanism with means to`insure` that the beginning end of workl introduced tothe mechanism will notpa'ss 'over the cutting'edge Vofi'thei slantingly mounted upper trimmer-knife,

and fail to be properly trimmed.

. With the above and` other objects in View, as willihereinafter appear, the invention` comprises .the devices, combinations, and arrangements 'of parts hereinafter Set forth and illustrated in the accompanying drawingsJ of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled `in the art.

In the accompanying drawings, Fig. l is a left end elevation of an overedge sewing machine embodying trimming mechanism according to the present invention. Fig. 2 is a partial front side elevation of the machine. Fig. 3 is a section on the line 3 3, Fig. l. of the ledger-blade and its carrier. Fig, 5 is a horizontal section on the line 5 5, Fig. 4. Fig. 6 is a disassembled perspective view of the ledgerblade carrier and support and Fig. 'l is a perspective View of the upper or movable trimmerblade removed from the machine.

Except as hereinafter more particularly described, the machine is constructed. substantially in accordance with the disclosure of my said copending application, Serial No. 278,393. Such a machine is constructed with a frame l including a pedestal 2 which supports the throatplate 3 through which work the curved eye-pointed needle and feed-dogs 5 and 5. Journaled in the frame l is the main-shaft 'l whichv` through t suitable connections, actuates the under looper and overedge looper 9. rEhe work passes over the throat-plate 3 and under the presser-foot it; being propelled by the feed-dogs 5 and d in the usual manner.

The main-shaft carries an eccentric i i which is connected by the pitman i2 to the upper trimmer-lever i3 fulcrumed at its rear end at ifi in the frame l and having atits forward end a head I5 in which is slantingly `mounted the up- Fig. 4 is a face view fil) `lola-de 22 thereagainst.

perftrimmer-blade `25S having at its lower end a cutting edge il, `Rising from the intermediate Wall i8`of the trimmer-blade i5 is the forwardly disposed" smooth surfaced upstanding guard-wall lwhich blocks the introduction of work on top of onabove-the cutting edge il, when thev blade I@ isat the lower limit of itsstroke below the level of the throatplate 3. Depending from the intermediate wall i8 is the rearwardly disposed wall- 2d, the lower end of which constitutes a pilot edge 2i against which the ledger-blade 2?. resta 'Bhe trimmer-blade headl l5 is guided at l'one 'end' againstlateral displacement by the hori- Zontallyadjustable block 23.` This block resists displacement of the working position of the upper blade i6 by the side pressure of the ledger- The ledger-blade 22! is adjustable lengthwise of itself in a guideway 2Q, Fig. 6; in the head 25 which is pivoted onthepin` 2@ carried by the depending ear 2l at the end of the cylindrical shank 23 longitudinally slidably adjustable horizontally in the pedestal 2 and held in set position by the set-screw 253. The ledger-blade 22 is clamped in the guideway 2d by the clampplate 3i! and screw 3l.

To bias the ledger-blade sidewise about its pivot 2B against the trimmer-blade l5 there is provided in a longitudinal bore in the cylindrical shank 23 a plunger 32 and biasing spring 33 which exert pressure upon the head 25, as shown in Figs. 3 and 5. It will be observed that the longitudinal axis of the pivot-pin 2@ is parallel to the cutting plane transversely of which plane the carrier 23 is adjustable. Also, the hingepin 26 which supports the ledger-blade 22 is parallel to the line of feed which, of course, is lengthwise of the presser-foot i@ and underlying feed-dogs 5 and i5.

The cutting plane may be adjusted transversely of the line of feed by lateral adjustment of the trimmer-blade head i5 on the lever I3 and corresponding adjustment of the ledger-blade carrier 23. The head l5 has in its rearward face a guideway 34 into which the free end of the trimmer-lever i3 nts and is expanded by the horizontally cisposed cylinder nut 35 in the split and socketed free end of the lever i3. entered by the trimmer-blade clamp-screw 35, as more particularly described in my said copending application.

It will be understood that the ledger-blade 22, by virtue of its hinge connection 26 with its carrier 28 is free to move against and be maintained by the spring 33 in sensitive shear-cutting relation With the trimmer-blade I, without any tendency to cramp or bind in the pedestal 2. Frequent grinding of the knives I6 and 22 is therefore not required.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a trimmer-mechanism for sewing machines, a frame, a 'trimmer-lever, means to actuate said lever, a trimmer-blade shiftably carried by said trimmer-lever for adjustment transversely of the direction of cutting movement thereof, a ledger-blade, a head on which said ledger-blade is removably mounted, a carrier on which said head is pivotally mounted on an aXis parallel to the cutting plane, and a spring to bias said head in a direction to yieldingly maintain said ledgerblade against said trimmer-blade, said carrier being mounted in said frame for bodily adjustment transversely of the cutting plane.

2. In a sewing machine, a frame, a pedestal thereon, a throat-plate on said pedestal, a carrier horizontally adjustable in said pedestal below said throat-plate, a ledger-blade head pivotally mounted on said carrier, a ledger-blade endwise adjustably mounted in said head, a spring to bias said head about its pivot, and a reciprocatory trimmer-blade into yielding engagement with which said ledger-blade is maintained by said Spring.

3. In a shear trimmer, the combination with a reciprocatory cutting blade, of a ledger-blade, a carrier on which said ledger-blade is pivotally mounted for movement into side engagement with said cutting blade, a spring for biasing said ledger-blade about its pivot in a direction to maintain said side engagement of said blades, and stationary guiding means to prevent lateral displacement of said reciprocatory cutting blade under the pressure of said spring.

4. In a sewing machine, a frame having a horizontal guideway, a carrier slidable in said guideway, means to x said carrier in a selected position in said guideway, said carrier having at one end a plate-like head, a plate-like ledger-blade head hinged to said carrier-head and formed with a ledger-blade guideway, a ledger-blade adjustable endwise of itself longitudinally of said guideway and Xed in a selected position therein, a reciprocatory trimmer-blade cooperatively related to said ledger-blade, and a spring to bias said ledger-blade head about its hinge connection with said carrier to maintain said ledgerblade in shearing engagement with said trimmerblade.

5. In a sewing machine trimming mechanism, a carrier having a tubular shank formed at one end with a depending ear, a plate hinged to said ear and formed in its outer face with a ledgerblade-receiving groove, a clamp overlying said groove, a screw passing through said clamp and into said plate, and a spring in said tubular shank arranged to exert pressure upon the inner face of said hinged plate.

6. In a trimmer-mechanism for sewing machines, a frame, a drive-shaft, a movable trimmer-lever mounted in said frame and actuated by said drive-shaft, a trimmer-blade carried by said trimmer-lever, a throat-plate, a ledgerblade, a head upon Which said ledger-blade is endwise adjustably mounted, a carrier on which said head is pivotally mounted on an axis parallel to the cutting plane, and a spring to bias said head in a direction to yieldingly maintain said ledger-blade against said trimmer-blade, said carrier with said head being mounted in said frame independently of said trimmer-lever and below said throat-plate for bodily adjustment relative to said trimmer-lever andl transversely of the cutting plane.

NICI-IOLAUS KNAUS. 

